// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/media/session/media_metadata_sanitizer.h"

#include <algorithm>
#include <string>

#include "content/public/common/media_metadata.h"

namespace content {

namespace {

    // Maximum length for all the strings inside the MediaMetadata when it is sent
    // over IPC. The renderer process should truncate the strings before sending
    // the MediaMetadata and the browser process must do the same when receiving
    // it.
    const size_t kMaxIPCStringLength = 4 * 1024;

    // Maximum type length of MediaImage, which conforms to RFC 4288
    // (https://tools.ietf.org/html/rfc4288).
    const size_t kMaxMediaImageTypeLength = 2 * 127 + 1;

    // Maximum number of MediaImages inside the MediaMetadata.
    const size_t kMaxNumberOfMediaImages = 10;

    // Maximum of sizes in a MediaImage.
    const size_t kMaxNumberOfMediaImageSizes = 10;

    bool CheckMediaImageSrcSanity(const GURL& src)
    {
        if (!src.is_valid())
            return false;
        if (!src.SchemeIsHTTPOrHTTPS() && !src.SchemeIs(url::kDataScheme) && !src.SchemeIs(url::kBlobScheme))
            return false;
        if (src.spec().size() > url::kMaxURLChars)
            return false;

        return true;
    }

    bool CheckMediaImageSanity(const MediaMetadata::MediaImage& image)
    {
        if (!CheckMediaImageSrcSanity(image.src))
            return false;
        if (image.type.size() > kMaxMediaImageTypeLength)
            return false;
        if (image.sizes.size() > kMaxNumberOfMediaImageSizes)
            return false;

        return true;
    }

    // Sanitize MediaImage. The method should not be called if |image.src| is bad.
    MediaMetadata::MediaImage SanitizeMediaImage(
        const MediaMetadata::MediaImage& image)
    {
        MediaMetadata::MediaImage sanitized_image;

        sanitized_image.src = image.src;
        sanitized_image.type = image.type.substr(0, kMaxMediaImageTypeLength);
        for (const auto& size : image.sizes) {
            sanitized_image.sizes.push_back(size);
            if (sanitized_image.sizes.size() == kMaxNumberOfMediaImageSizes)
                break;
        }

        return sanitized_image;
    }

} // anonymous namespace

bool MediaMetadataSanitizer::CheckSanity(const MediaMetadata& metadata)
{
    if (metadata.title.size() > kMaxIPCStringLength)
        return false;
    if (metadata.artist.size() > kMaxIPCStringLength)
        return false;
    if (metadata.album.size() > kMaxIPCStringLength)
        return false;
    if (metadata.artwork.size() > kMaxNumberOfMediaImages)
        return false;

    for (const auto& image : metadata.artwork) {
        if (!CheckMediaImageSanity(image))
            return false;
    }

    return true;
}

MediaMetadata MediaMetadataSanitizer::Sanitize(const MediaMetadata& metadata)
{
    MediaMetadata sanitized_metadata;

    sanitized_metadata.title = metadata.title.substr(0, kMaxIPCStringLength);
    sanitized_metadata.artist = metadata.artist.substr(0, kMaxIPCStringLength);
    sanitized_metadata.album = metadata.album.substr(0, kMaxIPCStringLength);

    for (const auto& image : metadata.artwork) {
        if (!CheckMediaImageSrcSanity(image.src))
            continue;

        sanitized_metadata.artwork.push_back(
            CheckMediaImageSanity(image) ? image : SanitizeMediaImage(image));

        if (sanitized_metadata.artwork.size() == kMaxNumberOfMediaImages)
            break;
    }

    return sanitized_metadata;
}

} // namespace content
